Luminescence with short decay time in arsenic chalcogenide glasses

Luminescence with decay time of about 10 nsec or shorter was found in a?As₂S₃ at 4.2 K on the high energy side of the luminescence observed by Kolomiets et al. From the dependence of the emission spectra on the excitation energy, it is interpreted as being due to the recombination of localized excitons.     

Dynamic mechanical properties of high molecular weight nylon 66 fiber

Dynamic mechanical properties of the ultrahigh molecular weight nylon 66 film and fiber produced by thermally induced solid-state polycondensation are presented. The α peak temperature of tan δ of these treated films and fibers is shifted 8–32°C higher than that of the appropriate control nylon 66 (film and fiber) while the maximum height of the tan δ peaks is decreased. The treated fibers have higher moduli at all temperatures (20–145°C) and humidities (30% RH) than do their control counterparts. The moduli of the treated fibers at 30% RH compare favorably with control yarn at 0% RH. These yarns also have a greater per cent of the 25°C modulus retention as temperature increases.     

Preparation of cyclosophoraose-A and its complex-forming ability

Cyclosophoraoses (CySs) are unbranched cyclic (12)--D-glucans produced by many strains ofAgrobacterium andRhizobium. Pure CyS-A, the group member having the smallest molecular size (degree of polymerization 17), was efficiently prepared by liquid chromatography using charcoal and ODS columns from the culture fluid of the mutant strain RA-12 fromR. phaseoli AHU 1133. The complex-forming ability of CyS-A was estimated from its enhancement of the solubilities of slightly soluble guest molecules in water using methods [I], [II], and [III]. In [I], an aqueous solution of CyS-A was shaken with the guest molecule, while, in [II], it was shaken with an acetone solution of the guest compound. In method [III], freeze-dried CyS-A powder was stirred with an acetone solution of the guest compound. The CyS-A cavity is thought to be able to accommodate three-dimensionally extended guest molecules,e.g., indomethacin. Method [II] was the best for obtaining CyS-A inclusion complexes, while method [III] would be recommended if the guest molecule is labile in the presence of water. Crystalline CyS-A inclusion complexes have not been obtained, but CyS-A complexes are expected to greatly enhance the solubilities of slightly soluble or insoluble guest molecules in water, because CyS-A is much more soluble than -cyclodextrin. Method [II] or [III] may afford a useful means of obtaining oily drug,e. g., vitamin E and K₁, in an amorphous state.     

Intégration analytique d'un système d'équations différentielles non linéaires dans le voisinage d'un point singulier,II

Résumé Nous avons formé dans le premier mémoire une solution formelle de(28.1) ordonnée suivant les puissances entière des solutions de(E). En annulant les Z_j qui correspondent aux polynomes de degrés différents de σ_v*(<σ_i*), nous obtenons une solution formelle (F _v). Dans le chapitre III, nous cherchons la condition suffisante pour la convergence uniforme de la série formelle (F _v). Dans le chapi tre IV, ce résultat est étendu au cas où la solution formelle dépend essentiellement des polynomes λ_j(x) de divers degrés. Le dernier chapitre est consacré à l'extension du théorème d'existence deM. M. Hukuhara qui joue un r?le important dans notre Mémoire.     

Saturable optical resonators with distributed Bragg-reflectors

Saturable optical resonators with distributed Bragg reflectors are analyzed by using the mode coupling theory. Hysteresis and nonlinear characteristics are given as a function of the absorption coefficient, the length of the absorber region, and the coupling coefficient of the corrugated waveguide. The calculated results show that the saturable optical resonator is useful as an optical gate, optical amplifier, and optical memory in integrated optical circuits.     

Simultaneous determination of the population densities of upper and lower laser states in metal vapor lasers

A method is proposed for determining the population densities of upper and lower laser states simultaneously by performing measurements, including perturbation spectroscopy and gain determinations. This method has been applied to the positive column of an He-Cd⁺ laser. It is shown that reliable results are obtained.     

The strong piezoelectricity in polyvinylidene fluroide (PVDF)

Polymers have been playing an important role already for a long time in electronic engineering as dielectrics. Recently a search has been made for polymers with unusual properties: organic semiconductors or photoconductors, electrets, and polymeric piezo — and pyroelectrics have been developed. And now, polyvinylidene fluroide (PVDF), a new piezoelectric film material is being produced on an industrial scale.^1,2 In this article, recent developments and applications of piezoelectric polymers are surveyed.     

Pico-second time-resolved luminescence spectra of excitonic molecules in CuCl

Transient luminescence behavior of excitonic molecules in CuCl is studied at 4.2 K with a time resolution of ～ 10 ps. The lifetime of the excitonic molecule state is determined to be several hundred pico-seconds. The spectral shape and the time characteristics of the luminescence intensity depend on excitation wavelength and also on the direction of observation. This is explained by the effect of the stimulated emission process.